Pathologies of the GI tract (which may include the pharynx, esophagus, stomach, duodenum, small bowel, and colon) include, among others, esophageal carcinoma, peptic ulcer diseases, colorectal carcinoma and inflammatory bowel diseases (e.g., ulcerative colitis and Crohn's disease). Early pancreatic cancer may manifest itself through neoplasms released into the small intestine by the pancreas. Gastric cancer is a major cause of death worldwide especially in Far East countries. The major type of gastric cancer is adenocarcinoma, which can be further categorized into an intestinal type and a diffuse type. Intestinal type lesions are frequently ulcerative and occur in the distal stomach more often than the diffuse type. These lesions are associated with a worse prognosis than the intestinal type. Colon and rectal cancers accounts for approximately 20% of all deaths due to malignant disease in the United States. Also, cancer of the pancreas is considered the fifth leading cause of cancer deaths in the United States. Other GI tract pathologies may include bleeding and disorders such as protein loosing enteropathy (PLE).
Delayed detection of GI tract cancers and other pathologies is a major factor contributing to an overall poor prognosis. Signs of early stages of GI tract cancers may be vague and nonspecific. The deep anatomical location of organs and parts of the GI tract may also add to the low yield of early detection. Often, gastrointestinal neoplasms arise in premalignant lesions which are only partially accessible or visible by regular endoscopy, laparoscopy or radiology.
Among known modalities used to distinguish normal from malignant tissue, are optically based techniques such as photodynamic diagnosis (PPD), also known as fluorescence diagnosis, and vital staining techniques, such as chromoendoscopy. Other techniques include the use of labeled tumor targeted molecules such as, labeled tumor specific antibodies. These techniques are based on specific accumulation of administered agents, such as monoclonal antibodies, photosensitizers (in PPD) or pigments (in chromoendoscopy) and detection of the accumulated agents.
These techniques are used in various medical fields. Radioactively labeled antibodies, typically intravenously administered to a patient, can be detected from outside the patient's body by a gamma camera, which can be universally found in all nuclear medicine departments. The image captured by the camera identifies the existence, location and extent of the radiolabeled pharmaceutical thus identifying the sites of tumor. Other detection methods utilize devices such as catheters, laparoscopes and endoscopes for the detection of the specifically accumulated agents. Integral illumination and imaging capabilities of these devices may be used for detecting photosensitizers and/or other pigments. Also, invasive devices or devices such as endoscopes (e.g., colonoscopes) may be equipped with a radiation detector for detecting radioactively labeled antibodies. For example, a colonoscope may have a scintillation crystal mounted on the tip of an optical fiber wave guide. The optical fiber is housed within a shielded tube which is inserted into the colonoscope and extends to within 4 mm of the open end of the colonoscope, the remaining length of the tubing serving as a collimator.
The use of gamma cameras from outside of the body may require a patient to be exposed to large amounts of typically high penetrating radioactive labeling. In vivo detection methods such as endoscopic (e.g., colonoscopic) examinations, usually require patient preparation and are typically stressful for patients, leading to low patient compliance and to low yield of early detection. Additionally, a large part of the GI tract (for example, most of the small intestine) is inaccessible to endoscopes. Thus, endoscopic examinations provide only a partial answer to the needs of early detection and they are not perceived as beneficial in wide scale screening for cancers.
There is thus a need for a patient friendly detection tool and method, capable of safely screening even the difficult to reach parts of body lumens, for early signs of diseases such as cancer.